1. Field of the Invention
The present invention relates to a variable length code (e.g., a Huffman code) decoding circuit.
2. Prior Art
When signal values of speech signals at respective sampling timings or signal values of dots (picture elements) of image signals are taken into consideration, a frequency of appearance of the signal values is not uniform. That is, some signals appear frequently, but some other signals do not appear so frequently. In recording or transmission of speech signals, image signals or the like, a variable length code such as a Huffman code is used as a code for representing each signal value. In this case, a variable length code having a small code length is assigned to a signal value which has a high frequency of appearance to compress data to be transmitted or recorded.
In order to decode a variable length code, it may be considered, for example, that the code patterns of variable length codes are prestored and when a code is inputted bit by bit, a code string comprising the bit or bits inputted up to that time is compared with each of the prestored code patterns, and this operation is repeated every time one bit is inputted. However, when such decoding processing is realized by software processing of a computer, a computation volume per input code is very large, and it is difficult to execute real-time decoding processing which follows an input bit rate of a code string. In addition, no simple apparatus for decoding a variable length code is available.